During a vehicle collision, there are commonly two impacts. In a primary impact, the vehicle impacts another object. In a secondary impact, a vehicle occupant impacts a component of the vehicle. For example, a vehicle operator sometimes impacts the steering wheel due to inertia. In order to help try to protect drivers from such secondary impacts, it has become common practice to use an impact-absorbing type steering column.
The structure of an impact-absorbing type steering column apparatus is such that when the driver suffers a secondary impact, the impact energy acts on the steering column in the frontward direction of the vehicle. The steering column or components thereof may detach from one or more fixation points with the vehicle body and move forward (e.g., in a collapse stroke), so that the impact energy is absorbed in the course of the collapse stroke. During a collapse stroke from a secondary impact, or other impact, components of the assembly will longitudinally collapse (e.g., generally within the volume it occupies within the vehicle in normal operation; that is, generally within its “footprint” in the vehicle), but generally will not collapse beyond a certain distance relative to a predetermined fixation point.
Notwithstanding efforts to improve internally collapsible steering column assemblies, there remains a need for alternative assemblies, particularly those in which assembly is simplified. There is also a need for improved or greater energy absorption during a secondary impact.